Ed Wiebe, Scientific Assistant at UVic explains the background on Twitter. The formation is known as a “fallstreak hole” in which a large gap, usually circular, appears in cirrocumulus or altocumulus cloud.

Wiebe explains that the fallstreak hole, also known as a “skypunch” is formed when the water in the centre of the cloud drops below freezing and enters a supercooled state but is not yet frozen, and begins evaporating away from a disturbance in the centre.

Three views of the same phenomenon, three and thirteen minutes after the first image. This is a fallstreak hole. Supercooled liquid water in the clouds rapidly changes to ice because of a disturbance near the centre of the hole. The disturbance spreads.#UVic#VictoriaBC 1/3 pic.twitter.com/jesDMCVTJy